Paving mixture and method of making the same



- UNITED STAT-ES PATENT OFFICE;

JosErR R. DRANEY, or RInoEwooD, N W JERSEY, assIeNoR; BY MESNE assren-MENTS, r BITOSLAG PAVING COMPANY, or NEW YORK, N. Y., A CORPORATION 0EDELAWARE.

PAVING MIXTURE D METHOD OF MAKING THE SAME.

1,364,621. Ito Drawing.

To all whom it may concern:

Be it known that I, JOSEPH R. DRANEY, a

' citizen of the -United States, residing at village of Ridgewood, inthe county of Bergen and State of New Jersey, have invented new anduseful Improvements in Paving Mixtures and Methods of Making the Same,of which the following is a specification.

. This invention relates to 'a pavement mixture as a product, the methodof making the same, and also to the final roadway or pavement having itswearing surface constructed from the product.

The invention contemplates, broadly: (1) the method of making animproved paving mixture or product, which method or pro-- cess consists,generally, in mixing with a mineral aggregate preferably of slag, aportion of a suitable filler material, such as pulverized limestone, orother finely divided substance; mixing with a bitumen binding agent,which is preferably blown or oxidized asphalt, the remaining portion of.the filler material; and then admixing these two mixtures to form thefinal paving material;

(2) a-paving mixture resulting from the r process above described andwhich is characterized by its homogeneity, density and wearingqualities; and (3) a roadway or pavement which has the ability towithstand the wear of trafiic to which it is subjected. By proceeding inaccordance with the method or process herein described, a paving mixtureis obtained in which the ingredients or materials are thoroughly andclosely amalgamated {the binding agent is properly distributedthroughout the mass, so that a homogeneous product is obtained in whichthe pulverized material "is thoroughly incorporated or impregnated withthe bituminous binding agent; and the voids between the particles ofmineral aggregate are filled.

to the desired percentage. The resultant paving mixture is impervious tostreet acids or other moisture and has the attributes of greatstability, and the capability of resisting deteriorationunder'temperature changes or the strain Qftrafiic to which itmay besubjected.

Application filed January 18,1917. Serial No. 143,030.

Specification of Letters Patent. Pate t d J 4 1921 A-roadway or pavementhaving its wearing surface constructed of the product above described ischaracterized b its wear-resisting qualities and by its, ability toresist deterioration, crawling, creeping, un'diie deformation, orfracture when .sub'ected to traflic wear, or adverse moistureand heatconditions. It will be'foundthat the wearing surface of the roadwa hasgreat durability, and sufficient rigi ity to stand up under traflicstrain, and yet 1t is suflici'ently malleable or resilient to preventchipping or breaking.

Havingset forth the particular objectsv of my invention, I will now givethe materials or ingredients which go to make up which is to take placewill occur before the slag is employed in the paving mixture.

Air-cooled blast-furnace-slag is very hard in character, has greattensilestrength, and

The molten I will not chip, crack or break when subjected to ..'ordinarytraflic' strains. The surfaces of the particles of slag are very rough,and as they are irregular in shape and slightly porous, or to be moreexact, cellular in makeup, the binding material used in the pavingmixture may, grip the particles of aggregate and hold them in position.-The physical characteristics of slag are such thata veryintimate-binding of-the slag aggregate and the binder will result,-with, of course, less tendency to separation under trafiic and greaterstabilityand less likelihood of disintegration under temperaturechanges, blag fraetureisirregular and rough sothat "close union can besecured betweenithe slag aggregate and the binder, and, furthermore,slag does not exhibit any appreciable ways a very considerable amount ofdust,

so that by reason of the smooth and dusty surfaces the stone does notgive as satisfactory binding areas as does slag. This is true of thelimestone and granite aggregates,

the surfaces of which are smooth, carry a considerable amount of dustand, being nonporous or non-cellular, fail to afford the irregulargripping area found in slag.

Any suitable filler material, such as pulverized limestone or Portlandcement, may be employed to fill the spaces or voids between theparticles of the mineral aggregate,

. but preferably I use a filler of pulverized slag or slag dust. .Due tothe inherent cementitious propertiesof-slag and its porosity cellularstructure, the binding agent will adhere closely to the particles ofslag-dust, and shifting of the fine particles of filler is guardedagainst. .As the bituminous binding agent, I employ blown or oxidizedasphalt which may be produced very economically from heavy asphalticbase petroleums. It is found that blown or oxidized asphalt is lessmalleable than asphalt whi-h is prodnced by other methods,-but whi e itscementitious'qualities are not as great as the usual distilled asphalt,yet it is characteri element of rigidity is such that. it maintains izedby its low susceptibility to moisture and temperature changes. Due toits rigidity, blown asphalt is particularly adapted for usein asphaltpavements for it has the necessary tensile strength to standup undertraffic strains without danger of disintegrating, and vyet it possessesthe necessary malleability or resiliency to resist cracking or. chippingand, additionally, its

the particles ofmineral aggregate and filler material against shiftinthe high cementitious qualityof distilled asphalt, for it becomes, byreason of oxidation, somewhat waxy-incha'racter and its facesfo stoneaggregates and for that reason ,has by some been heretofore regarded asof little value in paving mixtures; 1 I

Combined, howefver yvith slag, the a cities of which have'beenheretofore pointed out, it producesastrongly. adherent mixture,fornotwithstanding its relatively low cemerititious properties it ri sand adherestenaciously to the rough cc ular slag frac- 66 cause of. itscellular formation, is not particularly well adapted for use with theordinary asphalt cement, the reason for this being that the continuousabsorption of oil from the ordinary asphalt by the porous or cellularslag'soon results in a deadening of the asphalt due to loss of oil andthe disintegration of the asphalt binder.

The blown asphalt exhibits but little change under varying temperatures,and is, for that reason, more stable, and a pavement formed of a mixturein which blown asphalt or cement is used has greater and more uniformrigidity under all conditions, although it is resilient and malleableenough to be proof against chipping or fracture even under conditions oflow temperature.

In carrying out my improved process or method, I first select hard,air-cooled, blast furnace slag, preferably weathered, as hereinbefore.stated, and crush the same into 1 small particles, so that theparticles will pass through a screen of about one-fourth inch mesh:After careful screening, the slag mineral aggregate is graded into sizesso that, when mixed, the voids or-spaces between the larger particlesmay be filled by the particles of the next smaller size, and the voidsor spaces between-the second size of particles are filled by theparticles of the still smaller size, and so on down through the variousgradations. The graded mineral aggregate is dried and heated preferablyto a temperature between 350 and 4 and while hot itis-measured into asuitable mixing apparatus.

1 next divide the filler material into two portions, one of the portionsbeing, in wei ht, approximately equal to thirty-five (35% per cent. ofthe weight of the binding agent which is to be used in the mixture. Theother portion of the filler or pulverized material is added to theygraded and heated slag, the filler being added in a cold condition. Themineralaggregate and the added Y. pulverized material are thenmechanically Blown asphalt, as stated above, has-not" mixed 'u-ntiluniform and the filler is properly distributed throughout the mass ofthe slag aggregate. Y The asphalt composed iof blown or oxidized heavypetroleumbases is then melted in a kettle and, while it is-in moltencondition, there is added thereto the remaining 'portion of filler dustor fines, and, preferably, this portion of fines is equal to about 35%of the'weight of the bituminous binding agent. The asphalt is maintainedin molten condition and. is thoroughly agitated by any suitable means,so as to thoroughly and uniformly distribute the fines th-roughoutthemass of asphalt, and to keep the fines in suspension.

By mixing a} portion of fines, in substantially the amount, specified,with the blown-asphaltaa primed mixture is secured,

- the asphalt and fines, so that a very ready blending or mixing withthe remaining filler and slag is secured.

. Furthermore, this preliminary introduction of the fines into the blownasphalt takes up to a considerable extent thefree oil and gives amixture which isproperly tempered for mixing with the remainder of thefiller material and the aggregate.

' The next step of my process consists in adding the fines-impregnatedasphalt, in

a molten condition, to the heated mixture of slag and filler material,which has been previously measured into the mixer. The

resultant mixture is then thbroughly agitated, so that the finesimpregnated asphalt is thoroughly distributed throughout the mass. Uponcontinued stirring the sur-' faces of the particles of the mineralaggregate are properly coated with the asphalt, and the fines arethoroughlyv impregnated with the bitumen, so that a homogeneous anduniform paving'mixture is obtained.

The paving material resulting from the process above described iscapable of taking care of a' wide range of traffic conditions,

and may be laid on any suitable foundation, such as a concrete base, oldmacadam, old

brick pavements, or a layer of slag. After.

mixin the mineral a re ate fines and g C 9 7 binding agent in the mannerabove degeous over the use of distilled asphalt, in

scribed, the resultant paving mixture is placed in air tight vehiclesand transported to the location of the work. On arriving at the site,the mineral aggregate is dumped at a point sufficiently remote from itsplace of final deposition to allow all portions of v the load beingrehandled by the shovelers before final placing. It should be spread toa uniform depth upon the foundation previously prepared) and suitablyrolledso that it will surface.

I have foundthat: by proceeding in accordance with the method abovedescribed, a final paving mixture results, in which the bituminousbinding agent composed of provide a compressed wearing blown asphaltisthoroughly distributed" throughout the .mass. "The particles ofmineral aggregatesare properly coated and the asphalt is so thoroughlyincorporated with the pulverized material, that the 'interstices orpores of the pulverized material are filled "and an intimate and closeassociation of the mineral aggregate and filler with the.

as halt is obtained.

am aware that it is broadly old to use slag in paving mixtures, but itis to be noted that, in the present instanoe, the .slag. is-

employed in connection with blown or oxidized asphalt. pointed out,blown asphalt has, 'not 'the same cementitious properties as ordinarydistilled asphalt, but its use is advanta As has previouslybeenproperties, so that after the pavement is laid a chemical changetakes place in the slag, and a close chemical union is obtained betweenthe-slag and the blown asphalt.

Furthermore, as the slag particles are irregular in shape andare/characterized by their porosity or cellular structure, the asphaltwhen mixed with the slag will tend to flow into the pores, and thushair-like fingers are formed which grip the aggregate and hold it fast.As the own asphalt is characterized by its rigidity, and the mineralaggregate of slag by its inherent cementitious properties, irregularshape and porosity or cellular formation, there'is present-a very closebond or union between the particles of the aggregate and the blownasphalt. The blown asphalt tenaciously grips the particles of slag. sothat a very tough product is obtained. The mixture is very homogeneousand dense, and it IS only slightly susceptible to temperature changesand is characterized by its ability to resist street acids or othermoisture.

A roadwayformed with a wearing surface composed of-my improved productis very durable, economical and non-slippery, and pleasing to the eye.It possesses low susceptibility to temperature changes, great toughness,and suflicienti/rigidity to prevent creeping or deformation, and yet itis su'fliciently elastic or resilient to prevent.

craokin or chippin What I claim is 1. The process of producingasphalticf paving material, which consists in mixing a portion of thefiller material with a mineral aggregate of slag, mixing the remainingportion of the filler material with the bituminous binding agent, andthen admixing" the two mixtures thus formed.

2. The process of producing asphaltic paving material,.which consists inmixing a portion of thevfi ller material with a mineral aggregate ofslag, mixing the remaining portion of the filler vmaterial with abituminous binding agent of blown or oxidized asphalt, and then mixingthe two mixtures thus formed.

3. The process of producing asphaltic paving materlal, which consists incrushing the mineral aggregate composed of aircooled blast furnace slag,grading theslag, heating the slag, mixing with theheated and graded slaga portion of the pul,verizedfiller material, heatingthe .as phalticbinding agent to a molten-mass, adding the remaining portion ofthefiller material to the the fines, and then admixing the two mixmeltedbinding agent, and then admixing and thoroughly agitating the mixturesthus formed.

4. The process of producing .asphaltic paving material, which consistsin melting the bituminous binding agent, adding to the molten bindingagent a portion of the fines equal to approximately 35% of the weight ofthe binding agent, mixlng with a mineral aggregate of slag the remainingportion of of the asphalt, mixing with a mineral aggregate of slag theremaining portion of the fines, and then admixing the two mixtures thusformed.

6. An asphaltic paving material consisting of a mineral aggregate ofslag, a suitable filler material, and a binding agent composed of blownor oxidized asphalt.

7. An asphalt-i0 paving material consisting of a mineral aggregate ofair-cooled blast-furnace slag, a pulverized material, and a bindingagent composed'of blown or oxidized asphalt.

8. An asphaltic-paving material consisting of a mineral aggregate ofair-cooled blast-furnace slag, a filler nraterial composed of pulverizedor dust-like slag, and a binding agent of blown or oxidized asphalt.

9. A roadway comprising a suitable 'foundation and a layer thereonformed of a mineral aggregate of slag, a filler of pulverized material,and a binding'agent of blown or oxidized asphalt.

In testimony whereof I have hereunto set my hand.

' JOSEPH R. DRANEY.

